Use the Windows Snipping Tool. You'll find it via Start > All Programs > Accessories. (That's the route in Windows 7 but it should be similar in W10). Once you've found it, I suggest right-clicking on it and selecting 'Pin to taskbar'. Then you can access it more easily in future.
Once the snipping tool is activated you simply use your mouse (with the left button held down) to draw a rectangle around the relevant area. Then go to File > Save As to save it as a jpeg image. (You can then import that into a Word document, or similar, if you wish).